Object locator system



Juiy 12, 1949. P. A. JEANNE OBJECT LOCATOR SYSTEM 4 Sheets-Sheet 1 Original Filed Feb. 24, 1944 /Nl/ENTOR By PAJEANNE' ATTORNEY July l2, 1949. P. A. JEANNE 2,475,707

OBJECT LOCATOR SYSTEM Original Filed Feb. 24, 1944 4 Sheets-Sheet 2 A. JEANNE .j M

Arron/ver July 12,- 1949.

P. A. JEANNE OBJECT LOCATOR SYSTEM Original Filed Feb. 24, 1944 VOL TAGE 4 Sheets-Sheet 5 A TTORNEY July 12, 1949.

Original Filed Feb. 24. 1944 VOL TAGE P. A. JEANNE 2,475,707

OBJECT LOCATOR SYSTEM 4 Sheets-Sheet 4 mwsu/frfo PULSE nfrLccr/olvs Kuo/o Recs/ye@ aurpur THIS SPACING OEPENDENT CGV RANGE WV/T SETTING YA @D I 051.4 r livre-WAL {1l/llo 112i l l RANGE UNI T PULSE /nELA rev PuL ss [4100 nenn NorcH PuLse [[200 YARD NOT CN PULSE l l IExPA/voe swr-5P BY JM ATTORNEY Patented July 12, 1949 OBJECT LOCATOR SYSTEM Paul A. Jeanne, Mount Vernon, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a. corporation of New York Original application February 24, 1944, Serial No. 523,691, now Patent No. 2,416,320, February 27, 1947. Divided and this application March 19,

1945, Serial No. 583,536

Claims.

1 This invention relates to pulse operated systems and more specically to object locator and distance measuring systems employing indicating devices. This application is a division of applicaton, Serial No. 523,691, led February 24, 1944,

which issued as Patent No. 2,416,320 on February l The use of a cathode ray tube as an indicating or viewing device in an object locating and distance measuring system is well known in the art. In a typical arrangement, the cathode ray beam generated in the tube is deflected by means of a varying voltage, called the sweep voltage, applied to one set of deection elements so that it sweeps at a known rate over a predetermined path on a screen or target to provide a linear time scale or axis and the signals, such as echo signals, a visual indication of winch is desired on the screen of said tube, are applied to a. second set of deiiection elements in such manner as to cause transverse deections of the beam from its normal path. The disposition of the latter deections along a normal path as displayed on the screen indicates the time intervals existing between the signals and the width of each signal image indicates its time duration. In order that individual signals or restricted portions of the time scale of the cathode ray indicator tube may be closely observed, it is necessary in general to expand the scale beyond the available range of the screen. As a result of such sweep expansion, much of the total sweep range would be lost from view.

It is an object of this invention to provide a novel pulse-controlled object-locating system including an indicating device of the cathode ray type.

It is another object of this invention to provide a novel object-locating system including 'an indicating device in which a portion only of the timing scale thereof is expanded, the expansion being under the control of a pulse produced elsewhere in the system.

It is still another object of this invention to provide an object locating system including pulsecontrolled means for determining both the commencement and the duration of a time period in which a portion only of the timing scale of an indicating device, also included in the system, is expanded.

In accordance with a specific embodiment of the invention chosen by way of example for purposes of illustration, a sweep circuit is provided which comprises a sweep capacitor which is maintained in the charged condition by a sweep valve which is normally conducting, and a pulse generator called a. basic sweep timer which produces square pulses'of, for example, 600 microseconds duration once every 480th of a second which cuts ofi the sweep valve to allow the sweep capacitor to discharge through a tube whose anode-cathode path is connected across the sweep capacitor. This latter tube in the normal sweep circuit would probably `be called a constant curren tube but in the present circuit the current flow therethrough is maintained substantially constant at one value during those portions of the sweep cycle during which the time scale is not expanded but which has a pulse applied to its grid-cathode circuit to increase the'rate of discharge of the condenser through this tube for the length of time it is desired to expand the time scale. During the period of expansion the current flow is preferably maintained substantially constant at a higher value. The start of this pulse can be controlled so that any desired portion of the timing scale can be expanded. This control is analogous to that obtained by moving a, lens (magnifying in the direction of movement) along the scale of a slide rule. Moreover, the duration of the pulse can be varied to control the duration of the time scale expansion.

In the illustrative embodiment of the invention, the cathode ray indicating device is employed in a radar system, the indicating device being utilized to give a visual presentation of one or more echo pulses and, if desired, of direct pulses from the radar transmitter. A negative pulse (called the expansion notch), the initiation of which is controlled by a synchronizing pulse from the radar pulse transmitter operating through a variable delay circuit or unit (called the range unit), is utilized to produce 'a positive pulse which controls the discharge tube in the sweep circuit so as to expand the timing scale of the oscilloscope for the duration of the expansion notch which time interval, for example, may correspond to 1200` yards' range. This expansion notch or pulse is also applied to an amplifying circuit to produce an amplied negative pulse of the same duration which is applied to the cathode of the cathode ray tube to swing the potentialof the cathode negatively with respect to the control element therein and thereby increase the intensity of the beam for the period covered by the expansion notch or, in other words, for the period of time that the time scale is expanded.

The invention will be more readily understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof in which:

Fig. 1 is a schematic block diagram of an indicating system employing a sweep circuit in accordance with the invention;

Fig. 2 is a circuit diagram of a portion of the system shown in Fig. 1; and

Figs. 3 to '7 inclusive are dagrammatical representations to aid in understanding the invention.

Referring more specically to the drawings, Fig. 1 shows, by way of example for illustrative purposes, a radar system using a sweep circuit in accordance with the invention. Fig. 1 is a single line block diagram to show the relationship of the various major elements of the system and is not intended to be a circuit diagram. In the arrangement of Fig. 1, a high voltage rectifier I in the radar purse transmitter 9 supplies about 12,000 volts direct current to a suitable charging circuit or element II capable of producing a still higher voltage. After the charging voltage builds up to about 21,000 volts a rotary spark gap I2 discharges the capacitor in the charging circuit. This discharge takes place in about 1 microsecond and causes a magnetron oscillator in the radio transmitter I3 to oscillate for this brief period and send short pulses of radio frequency energy through a T-R box I4 to an antenna I5 which, for example, includes a wave guide and a parabolic .reecton A suitable antenna is disclosed in an'application by A. P. King, Serial No. 499,450, iiled August 21, 1943. Radio frequency pulses from the antenna (called transmitted pulses or "emitted pu1ses) strike one or more objects and produce reflections or echoes therefrom which are received by the antenna I5 and transmitted through the T-R box I4 to the receiver I6. The T-R box may be of any desirable type, for example, that employing a Western Electric Company 709A tube in a resonant cavity. This tube is nlled with an ionizable gas and has a small gap therein. During reception of the low voltages of the receivedvenergy the gas is not ionized, the cavity is tuned to resonance and the received energy is applied to the receiver I6. During the transmission of a pulse from the radio transmitter I3, the voltage due to the pulse ionizes the gas, thus detuning the cavity and substantially preventing the energy of the pulse from reaching the receiver I6. l

In the receiver I6 the received waves are heterodyned to a convenient intermediate frequency and these intermediate frequency waves are amplified, detected, amplified and applied to one of the vertical defiecting plates I1 of a cathode ray oscilloscope I8. The received waves cause, for example, a sharp upward deflection of the trace of the cathode ray beam generated in the tube I8. A typical trace is shown in Fig. 7A, the pulse I I 0 representing the transmitted pulse and the pulse I I I being caused by reflections from targets.

Energy from the rotary spark gap I2 (which is in the nature of a synchronizing pulse) controls the sweep circuit I9 which, by means of the connections 20 and 2| to the deflecting plates 22, causes the cathode ray beam to sweep across the screen once per pulse. Energy from the rotary spark gap is also fed into a variable delay circuit or unit 23 (the range unit) which produces a sharp pulse I I2 a controllable period of time after the initiation of each pulse in the rotary spark gap. A suitable range unit is disclosed in an application of L. A. Meacham, Serial No. 491,791, filed June 22, 1943, which issued June 17,

1947, as Patent No. 2, 422.204. The output pulse from the circuit 23 which is shown in Fig. 7-B is feci to an expansion notch generator 2l which produces a negative pulse II5 which has a duration corresponding, for example, to a range of 1200 yards. This pulse is shown in Fig. 7-E. A suitable circuit for producing such a. pulse is disclosed in an application of B. M. Oliver, Serial No. 486,780, iiled May 13, 1943, which issued as Patent No. 2,433,863 on January 6, 1948. This pulse is applied to the sweep circuit I9 to make a controllable portion of the sweep voltage wave produced by this sweep circuit of a greater voltage gradient than the rest of the wave and thus to expand in the direction of the sweep the pattern on the oscilloscope screen for a distance corresponding to the length of this pulse. A portion of the energy from the sweep circuit I9 is also applied by means of a connection 25 to an unblanking circuit 26 to release the beam. which has been previously blanked off, for a period of about 6001microseconds after the initiation of each pulse from the rotary spark gap I2.

The pulse from the variable delay circuit 23 is also connected through a delay circuit 21 which delays the pulse for a period corresponding to about 400 yards range by producing a pulse II3 which is delayed from the pulse II2 by a period corresponding to a range of 400 yards. A suitable delay circuit is disclosed in the above-identified Cliver patent. The delay interval is shown in Fig. 7-C. The delayed pulse is applied to a pulse generator 28 (called the "40G-yard notch generator) which is, for example, similar to the expansion notch generator 24 except for some differences in circuit constants. This circuit generates, as shown in Fig. 'Z-D, a pulse II4 of a duration corresponding approximately to 400 yards range. The output of the generator 28 is connected to the other one of the deflecting plates I1 in such a Way that the energy of the notch is added to the energy from the receiver I6 so that an echo pulse appears in the notch in the image on the oscilloscope screen in the manner shown in Fig. 6 with respect to one echo signal. The complete representation is shown in Fig. 7-F.

Energy from the expansion notch generator 24 is amplified in the intensifier circuit 29 and applied as a negative pulse to the cathode 30 of the oscilloscope I8 to increase the intensity of the beam for the duration of each pulse from the generator 24.

Reference will now be made to Fig. 2 which shows suitable circuit diagrams for the elements I9, 26 and 29 of the arrangement of Fig. 1. The circuit of Fig. 2 comprises a sweep circuit, an unblanking circuit, and an intensifier circuit.

The sweep circuit proper consists essentially of a diode 44 which passes negative pulses only, a single pulse multivibrator comprising the tubes VI and V2 and called the basic sweep timer for triggering the sweep from the 10- to 30-volt negative pulses supplied from the rotary spark gap I2 in the transmitter, a sweep valve tube V3 by means of which the sweep condenser 3I is charged, a discharging tube V4 through which the condenser 3I is discharged at one substantially constant `rate for the entire discharge portion of the sweep cycle except for the period during which it is desired to expand the time scale when it is discharged at a faster, and preferably constant, rate, a sweep voltage divider 32 and 33, and an inverter tube V5. Individual power supplies can be provided for each of the ancdes of many of the tubes have been shown connected through respective anode resistors to the positive terminal of a 45o-volt direct current source 34 the negative terminal of which is connected to ground, and the anodes of others of the tubes have been shown connected through respective anode resistors to the positive terminal of a 300,-vo1t`direct current source 35 whose negative terminal is grounded.

Negative to 30-volt pulses of about 1.2 microseconds duration are supplied to the terminals 40 and 4| of the sweep circuit. A conventional coupling condenser 42 and a leak resistor 43 are provided in the input circuit of the tube VI along with the diode 44 which is yconnected in the grid lead of the tube VI so that'negative pulses only are passed. Eight of these pulses which are substantially concurrent with the transmitted pulses are shown in Fig. 3-A. The tubes VI and V2 comprise a single pulse multivibrator which produces relatively square negative pulses at least 600 microseconds long. the duration of the longest sweep. As there are. for example, 480 pulses per second from the spark gap I2, there are intervals of more than 2,000 microseconds between transmitted pulses and the inactive periods are over 1400 microseconds long. These negative sweep timing pulses produced by the basic-sweep timer" (see Fig. 3-C) are applied to the grid of the tube V3.

Considering now the "basic sweep timer in somewhat greater detail, the anode of the tube V| is connected through a coupling condenser 45 to the grid of the tube V2 while the anode of the tube V2 is connected through a. coupling condenser 46 to the grid of the tube Vl. A leak resistor 41 -is connected between the grid of the tube Vl and ground, and a leak resistor 48 is similarly connected between the grid of the tube V2 and ground. Plate voltage for the :inode of the tube V| is supplied from the source 34 through the resistors 49 and 50, the common terminal oi these two resistors being connected to ground through a condenser 5|. Anode Voltage for the tube V2 is provided by the source 34 through resistors 52 and 50. The cathode of tube VI is connected to ground while the cathode of tube V2 is connected to ground through resistor 53. The cathode of tube V2 is connected to the positive terminal ofthe source 34 through resistors 54 and 50. A diode 55 is connected between the grid of tube V2 and ground for stabilization purposes.

The action of the multivibrator circuit for generating substantially square negative pulses of the type shown in Fig. 3-C for basic sweep timing will now be described. Statically when no pulses are being received from the transmitter. the tube VI is passing current while the tube V2 is biased to cut-oil. Therefore, the voltage at tbe plate of V2 is the full Voltage of the source 34 (approximately 450 volts), while that of the plate of the tube V| is less by the drop through the resistors 49 and 50.

tubes VI and V2 are charged to the voltages of vtheir respective plates, condenser 46 being charged at a higher potential. The negative synchronizing pulses applied between the terminals 40 and 4| from the transmitter serve only to trip the circuit, that is, start the action of the multivibrator. When one of these pulses is applied to the grid of the tube VI it tends to drive this tube to cut-oli causing a decrease in current through resistor 49 and a resultant rise in volt- Furthermore, condensers 45 Vand 45 which couple the plates and grids of the age in the plate of the tube Vl. As this voltage rises, condenser 45 charges to a higher potential causing the grid of the tube V2 to become more positive and the tube V2 to begin to conduct. Thus the current through the resistor 52 causes a drop in voltage at the plate of the tube V2 and sends a negative impulse through the condenser 46 causing the grid of the tube VI to become more negative, further cutting off this tube. The above action, once started by an incoming negative synchronizing pulse (such as one of the pulses |05 shown in Fig. 3-A or pulses having a xed phase relationship with respect thereto), is very rapid and continues until tube VI is cut oil? and tube V2 is passing current. The tubes will remain in this condition until the grid of tube Vl is suiciently recovered from the negative pulse through the condenser 46 to permit tube VI to become conducting again. This depends on the time required for the condenser 45 to discharge through the resistor 41. The values of resistance and capacitance are so chosen that the tube VI -will remain cut oil? for approximately 600 microseconds. The tubes then restore very rapidly to their initial condition. The output of the basic sweep timer at the plate of the tube V2 isa substantially square negative pulse due to the rapid drop and rise of voltage at this plate. Eight of these pulses |02 are shown in Fig. 3 0. This is the pulse needed to cut oi the sweep valve tube V3. In the action just described. the condenser 45 has attained a charge above its initial static condition when the voltage at the plate of the tube VI rose and it must be discharged before initial conditions can again be realized. Also it is desirable to discharge this capacitor quickly which can not be done through the grid leak 48. The diode 55 is used to provide a low impedance discharge path to ground for this condenser and the multivibrator circuit is thus restored very rapidly to its initial condition before another incoming negative pulse is applied.

'I'he circuit constants of the sweep circuit shown on the drawing are such that the maximum sweep time is about 600 microseconds corresponding to a range of about 100,000 yards. The sweep expansion resistor 56 in the cathode of the discharge tube V4 permits adjustment of the maximum sweep from approximately 44,000 yards to 100,000 yards.

In the absence of a sweep timing pulse |02 from the basic sweep timer, the sweep valve tube'V3 is normally passing current to charge the sweep condenser 3| through a circuit which includes ground, the sweep condenser 3|, the cathode-anode path of the tube V3, resistor 51, and the direct current source 34. When one of the basic sweep timing pulses I 02 is applied to the grid of the tube V3 through the coupling condenser 54A, the current charging the sweep condenser 3| is interrupted and the condenser discharges through the discharge tube V4 at a constant rate (in the absence of a pulsefrom the notch expansion generator 24). 'I'he rate of discharge is determined by the characteristics of the tube V4 and the value of the resistance 56 which is shunted by the cony denser 58. The output of the generator 24 is ap- 7. ing to a wave travel of 1200 yards. and these are amplified and phase inverted by the element 36 to become square wave positive pulses which are fed to the grid of the tube V4 and also to the grid of thetube V1 in the. intensifier circuit which will be described below. .The positive pulses applied to the grid of the tube V4 cause this tube to pass a greater current for the duration of the 1200- yard notch, or in other words for a short time on either side of the 440G-yard pulse produced by the notch generator 28 and which is, as shown in Fig. 5, centered in the 1200-yard notch pulse H5. The faster discharge of the sweep condenser 3| increases the sweep speed vand therefore expands the sweep during the occurrence of the 7.2 microsecond pulse |||5. Fig.v 3-D shows direct sweep pulses |03 produced across the sweep condenser 3| in the absence of notch expansion pulses II5 at the tube V4, while Fig. 3E shows sweep pulses |04 produced under these conditions in the output of the amplier inverter tube V5. Fig. 3-G shows the timing of the notch pulses and notch expansion pulses with respect to the transmitted signal pulses shown in Fig. 3-A

While the same relation is shown, on a larger scale,

in Figs. '-D and 7-E. It will be noted that each notch pulse I I4 lags its corresponding transmitted pulse I I0. This lag is also shown in Fig. 6, which is a combination of Figs. 4 and 5, and wherein pulse I I is the transmitted signal pulse after reception and detection and pulse III is the echo pulse bracketed by the 40o-yard notch pulse II4. Fig. 4 shows the pulses ||0 and alone while Fig. 5 shows the pulse I I4 with respect to the time position of the pulse H0. The 400- yard notch pulse ||4, as pointed out above and as shown in Fig. '7, is started 400 yards after the pulse ||2 produced by the range unit 23. The expansion notch generator 24 produces a pulse I I5 which starts with the pulse produced by the range unit 23 and extends over a period corresponding to a range of 1200 yards, or, in other words, it starts 400 yards before the starting time of the pulse I I4 produced by the notch generator 28 and extends for a time interval corresponding f to a o-yard range after the notch pulse I|4 has been completed. Thus the sweep wave is said to be expanded during the occurrence of the pulse from the expansion notch generatorl 24. This period of notch expansion is shown by the portions |01 in the pulses |06 in Fig.- 3-I-I. Referring again to Fig. 6 it is noted that the direct pulse I|0 appears narrower than the echo pulse I I This is because there is no expansion during the reception of the direct signal, hence it appears narrower than the echo.

The wave shown in Fig. 3-H is applied through condenser 6I to one of the deflecting plates 22 in the cathode ray tube I8. A voltage 180 degrees removed from the voltage wave shown in Fig, 3--H is applied to the other of the deflecting plates 22 by means of the condenser 62 which is connected to the plate of the amplifier-inverter tube V5. The grid of the tube V5 is connected by means of the resistor 63 to the common ter minal of the'condensers 32 and 33. To drive the inverter V5, abouta tenth of the total sweep voltage across the condenser 3| is taken from the voltage i divider formed by the condensers 33 and 32. The amplification in the tube V5 produces an output approximately equal to the direct sweep voltage applied to one of the plates 22 by means of the condenser 6|. Bias for the tube V5 is provided by means of a resistor 64 while the grid leak resistor 65 is connected in the circuit 8 between the grid of the tube V5 and ground. The diode 66 is connected across the condenser 32 in such manner that positive current is conducted to ground. Under static conditions, this prevents the condenser 32 from maintaining any positive potential above ground when charge is received through the sweep valve V3 and the condenser 33. Under dynamic conditions when the sweep condenser 3| is discharging, condenser 33 also discharges drawing its discharge current through the condenser 32 since the diode 66 will not conduct current in this direction. A negative pulse is thereby impressed on the grid of the amplifierinverter V5 producing the required positive pulse in its output. The effect of the diode 66 under dynamic conditions is therefore to stabilize the initial potential impressed on the input of the inverter V5 at the beginning of each sweep, this initial potential being limited to approximately that of ground. Without the diode 6B, variations in the time interval between successive signals from the fixed average would cause some fluctuations in the horizontal deflecting force, thereby some fuzziness of the image since images of successive signals would not exactly coincide on the screen. The function of the inverter V5 is to reverse the phase of the voltage |03 and produce inverted sweep pulses |04 so that the eiects produced by the two horizontal deflecting plates 22 on the beam are additive. that is, when one plate attracts the beam, the other repels it.

The longest sweep impulse lasts about 600 microseconds so that at the rate of 480 per second, l

the inactive intervals between sweep impulses are 1400 microseconds or more. If the electron beam struck the screen continuously a bright spot would be produced at the start ofthe, sweep and the return of the beam would be visible across the screen. To eliminate these undesirable features, the beam in the cathode ray tube I8 is normally blanked oif by fixing the static or continuous biasing voltage of the grid 31 therein at a suiliciently vnegative value to cut the beam off and positive pulses suiiicient to release the beam are applied to the grid only during the interval when sweep impulses are applied to the horizontal deilecting plates-22. The biasing voltage is applied to the grid 31 from tap 14 of the potentiometer 10 connected across a suitable constant source of power (not shown). 'I'he cathode 30 is connected to a tap 1| thereon through a resistance 12 and one of the focussing anodes 33 is connected by means of the tap 13 to a point on the potentiometer 10 which is positive with respect to the potential of the cathode 30. The control element 31 of the cathode ray tube is connected to the tap 14 on the potentiometer 10 (which is negative with respect to potential of the cathode 30) through the resistor 115. The second anode 39 of the cathode ray tube is connected to a tap 16 on potentiometer 11 which is connected to a second v power supply (not shown). This is done to provide means for placing the second anode at the average potential of the plates I1 which are directly connected 'to the'receiver output tube. The tap 16 is at a positive potential with respect to the potential of the tap 13 on the potentiometer 10. The values of the potentials applied to the members 30, 31, 33 and 33 are chosen, in accordance with well-known practice, so as to produce a. fine spot on the screen 18.

The circuit arrangement for generating the unblanking pulses comprises the tube V6 and associated circuit connections. The square negative pulses from the' output of the basic sweep timer cordanc'e with the invention. which has been ac- 80 to the control grid of the tube V6. The grid leak resistor 8l is provided between the control grid and ground, the cathode being connected` directly to ground. The anode of the tube V6 is connected through resistor82 to the positive terminal of the source 35 and through coupling condenser 83 to the control element 31 of the cathode ray tube I8.

The sharply-peaked negative voltage across the resistor 8l in series with the coupling condenser 80 is applied to the control grid of the tube V5,

` driving this tube to cut-oil by the time each negative pulse |02 shown in Fig. 3-C has reached but a small fraction of its ultimate value. Thus the output voltage at the plate of the tube V6 rises sharply due to the decreased voltage drop through its plate resistor 82. The voltage of the plate remains at this increased positive valueunblanking pulses are shown as the pulses |05 in Fig. 3-F. The time that the grid of the tube V6 is held below the cut-oi voltage determines the durationof the unblanking pulse. As mentioned above, this time is about 600 microseconds.

Due to the fact that the beam is swept at a faster rate across the screen during the time of expansion, the image on the screen during that period of time is not as bright as for the rest of the image. To compensate for this an intensifier circuit comprising the tube V1 and its associated circuit conections has been provided. Positive pulses corresponding in time duration to the 1200-yard negative pulse' I I5 produced by the expansion notch generator 24 are applied to the grid of the tube V1 through the coupling condenser 90 and resistor 9|. A grid leak resistor 92 is connected between the common terminal of the members 9U and 9| and ground and the cathode of the tube V1 is connected to ground through the biasing resistor 93. The anode is connected through the anode resistor 94 to the positive terminal of the source 35. The action of the tube V1 is to amplify each positive pulse applied to its grid to produce a negative pulse which is applied to the cathode 30 of the cathode ray tube I8 through coupling condenser 95. This causes the cathode of the tube I8 to swing in a negative direction to intensify the beam during the period of time spanned by the pulse produced by the expansion notch generator 2.4. This period is represented between the points A and B in Fig. 5 and in Fig. rI-F. l

It will be apparent that by making use of the circuit arrangement described above, the linear time scale is expanded between the points A and B of Fig. 5 and of Fi g. "I-F and the positions of these points with respect to the transmitted pulse III) can be varied by varying the time of generation of the pulse in the range unit 23. Thus if the range unit pulse I I2 is generated after a shorter time interval following the corresponding pulse IIII, the period of expanded sweep shown in Fig. 5 and Fig. "I--F moves to the left as does also the 40G-yard notch pulse H4 which is always centered within the period of the expanded sweep. The pulse H4 is centered with respect to the selected echo I I'I either by manual means or by any suitable automatic means.

Circuit constants of an arrangement in ac- .have been indicated on the drawings.

tually constructed and satisfactorily operated It is to be understood. however, that the invention is not limited to the use of elements having these particular circuit constants asit is obvious that changing the, frequency of pulsing, the length ofv the pulse produced by the expansion notch generator or varying the length of the sweep timing pulses are examples of various changes which might be made and which will cause changes inv the circuit constants. y v

Although the present invention has been described in terms of the preferred illustrative em'- bodiment, it will be realized that the invention and its several features are susceptible of embodiment in a wide variety of other forms and hence the invention is to be understood as comprehending such other forms as may' fairly come within the spirit and letter of the claims.

What is claimed is: v

1. In a radio object-locator system, means for generating a voltage pulse, a sweep circuit for generating a sweep wave adapted to deect an electronic beam, means responsive to said pulse for generating a second Apulse of longer duration, means for utilizing said second pulse to control said sweep circuit to similarly vary the gradient of said sweep wave for a period of time corresponding to the duration of said second pulse, means responsive to said rst pulse for producing a third pulse whose tim'e span is centered in the time span of said second pulse, a cathode ray tube comprising means for generating a beam of elec`- trons, a screen or target for said beam, and two sets of deiiecting elements positioned to cause deflection of said beam in two coordinate' directions 90 degree apart, a source of variations to be depicted on said screen, said source including a radio object-locating transmitter and receiver, means for applying said third pulse and said last-mentioned variations to one of Isaid sets of defiecting elements, and means for applying said sweep wave to the other of said two sets of deflecting elements.

2. In. a radio object locator system, means for transmitting from an observation point to an object distant from said point a train of energy pulses or waves spaced apart in time, means at said observation point for receiving reections or echoes of said pulses from said object, means for generating a control pulse delayed by a controllable period of'time after each of said transmitted pulses, means for generating a sweep wave, means for initiating the sweep wave, means responsive' to each of said control pulses for generating a pulse of longer duration, means for utilizing said pulses of longer duration to control said sweep circuit to vary the gradient of said sweep wave for a period of time equal to the duration of said longer pulse, means responsible to said control pulse for producing a pulse whose time span is centered in the time span of said longer pulse, a cathode ray tube comprising means for generating a beam of electrons, a screen or target for said beam, and two sets of'deecting elements positioned to cause deflection of said beam in two coordinate directions 90 degrees apart, means for applying the received echo pulses and said centered pulse to one of said sets of deecting elements, and means for applying said sweep wave to the other of said sets of de- 'l1 for generating a series of pulses and for transmitting saidpulses to an object distant therefrom to thereby produce echo signals at the transmitting point, an indicating member including a cathode ray device having two sets of deile'cting elements associated therewith, means for applying said echo signals to one set of said deilecting elements. a generator of sweep waves of the type in which each wave has a part of the sweeping portion thereof wherein the gradient is dierent from the gradient of the rest of the sweeping portion thereof means for applying said from to thereby produce echo signals at the transmitting point, an indicating member including a cathode ray device having two sets of deilecting elements associated therewith, means for applying said echo signals to one set of said deflecting elements, a generator of sweep waves of the type in which each wave has a part of the sweeping portion thereof wherein the gradient is diierent from the gradient of the rest of the sweeping portion thereof, means for applying said sweep waves to the other set'of deecting elements, means separate from said sweep waves generator and responsive to the pulses produced by said pulse generating means for producing pulses of longer duration than said first-mem tioned pulses for controlling both the commencement of and the duration of said part of different gradient, and means for varying the time position of said last-mentioned pulses.

5. An object locating and distance measuring system comprising means' at a transmitting point forgenerating a. series of pulses andfor transmitting said pulses to an obplect distant therefrom to thereby produce echo signals at the transmitting point, an indicating member including a cathode ray device having two sets of detlecting elements associated therewith, means for applying said echo signals to one set of said deilecting elements, avgenerator of sweep waves of the type in which each wave has a part of the sweeping portion thereof wherein the gradient is different from the gradient oi Athe rest vof the sweeping portion thereof, means for applying said sweep waves to the other set of deectingelements, means separate from said sweep waves generator and responsive to the pulses produced byrsaid pulse generating means for producing pulses of longer duration than said first-mentioned pulses for controlling both the commencement of and the duration of said part of diierent gradient. and means for varying the time position of said last-mentioned pulses, each of said pulsesy of longer duration being at least three times as long as each of said mst-mentioned pulses.

PAUL A. JEANNE.

REFERENCES CITED The following referenices are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,924,174 Wolf Aug. 29, 1933 2,145,724 Horsley Jan. 31, 1939 2,189,549 Hershberger YA Feb. 6, 1940 2,295,293 Rogers Sept. 8, 1942 2,300,199 Wolff Oct. 27, 1942 2,409,462 zworykin oct. 1x5, 1946 2,416,088 Deerhake Feb. 18, 1947 2,426,201 Grieg Aug. 26, 1947 2,453,711 Isbister Nov. 16, 1948 

